what is Cluster?

My name is Ros and I'm going to tell you about four satellites called Cluster II. Cluster is the name given to four satellites which are orbiting the Earth in a special formation. These satellites are being used to study a part of the Earth’s space environment called the magnetosphere. You can learn more about the magnetosphere in "Ringing the Magnetospheric Bell" in our "Sun-Earth Connection" section.

On June 4th 1996, the Ariane 5 rocket rose up from its launch pad with the Cluster satellites on board. Less than 60 seconds later, there was huge explosion and smoke clouds filled the sky. It was a disaster for the scientists who had worked so hard for 15 years designing and building these satellites. They were so upset and convinced that the spacecraft had important work to do that they decided to build another set of Cluster satellites.

The first quartet of Cluster satellites was destroyed when Europe's Ariane 5 exploded soon after launch on June 4, 1996.

An agreement was reached between Russia and ESA that the new satellites would be launched (two at a time) from Baikonur, in Kazakhstan. Using a modified version of the Soyuz rocket used to launch the first man into space nearly 40 years earlier, the two launches in July and August 2000 were successful and the Cluster II spacecraft began their new mission.

Here are some photos of the Cluster satellites before and during launch. The satellites were carefully stacked one on top of another and packed into the top part of the rocket. You can get an idea of how big each of the spacecraft is by comparing them to the person (dressed in light blue) in the bottom left hand corner of the photo.

When they reached the right height, the satellites were released into orbit and eventually positioned in formation.

The four Cluster satellites orbit the Earth in formation gathering data which is sent back to the scientists.

Here is the movie of the blast off from Baikonur of a pair of Cluster II
satellites aboard a Starsem Soyuz equipped with a Fregat upper stage.

This animation shows how the Cluster II satellites were deployed after launch.